IPPW-6 25 June 2007 Grover -1 The Phoenix Mars Landing An Initial Look Presented by M. R. Grover 1 E. S. Bailey 1, J. P. Chase 1, B. D. Cichy 1, P. N. Desai 2, D. B. Eldred 1, P. E. Laufer 1, M. E. Lisano 1, J. L. Prince 2, E. M. Queen 2 and E. D. Skulsky 1 1 Jet Propulsion Laboratory, California Institute of Technology 2 NASA Langley Research Center International Planetary Probe Workshop 6 25 June 2007 Atlanta, Georgia, USA National Aeronautics and Space Administration Jet Propulsion Laboratory, California Institute of Technology

IPPW-6 25 June 2007 Grover -2 Acknowledgements Special Acknowledgement: Lockheed Martin Phoenix Entry Descent & Landing Team T. D. Gasparrini B. R. Haack M. A. Johnson T. M. Linn T. A. Priser J. A. St. Pierre And the entire Lockheed Martin Phoenix Team

IPPW-6 25 June 2007 Grover -3 Landing Analysis Maturity The contents of this presentation represents present understanding of the Phoenix landing. A rigorous analysis of the Phoenix landing is currently underway and a more complete and thorough assessment will be available in coming months.

IPPW-6 25 June 2007 Grover -4 The Phoenix Story Started as Mars Surveyor 2001 Lander –Faster, better, cheaper spacecraft –Sister spacecraft of Mars Polar Lander –Cancelled after Mars Polar Lander failure in 1999 Not enough time to address findings of MPL failure review prior to 2001 launch window Reborn as Phoenix in 2003 –Same spacecraft, modified science payloads –Enhanced radar –Addition of EDL communication system –Enhanced test program –Launched Aug 4 th, 2007

IPPW-6 25 June 2007 Grover -5 Spacecraft Overview Pre-Entry Configuration Entry Configuration Terminal Descent Configuration Parachute Configuration Post HS & Leg Deploy Configuration

IPPW-6 25 June 2007 Grover -6 Parachute Phase Radar Activated: E+295s, L- 138s Heatshield Jettison: E+235s, L-198s, 11.0 km, 120 m/s Parachute Deployment: E+220s, L-213s, 12.6 km, Mach 1.65 Peak Heating: 46 W/cm 2 Peak Deceleration: 9.2G Cruise Stage Separation: E-7min Lander Separation: E+390s, L-43s, 0.98 km, 56 m/s Gravity Turn Start: E+393s, L-40s, 0.80 km Constant Velocity Start: E+414s, L-19s, km Touchdown: E+434s, L-0s, 0 km, Vv=2.4 ±1 m/s, Vh<1.4 m/s Entry Turn Starts: E-6.5 min. Turn completed by E-5min. Leg Deployments: E+245s, L-188s Dust Settling: L+0 to L+15min Landing at -3.9 km elevation (MOLA relative) Entry Prep Phase Begin Gyro-Compassing: L+5min Solar Array Deploy: L+16min * Entry altitude referenced to equatorial radius. All other altitudes referenced to ground level Final EDL Parameter Update: E-3hr; Entry State Initialization: E-10min Terminal Descent Phase Hypersonic Phase Entry: E-0s, L-434s, 125 km*, r= km, 5.6 km/s,  = deg Feb 2008 Note: Information in this graphic represents a nominal entry (C ). Dispersions exist around all values. EDL Nominal Design

IPPW-6 25 June 2007 Grover -7 Final Approach EFPA Knowledge 3σ shallow 3σ steep Design EFPA Corridor TCM-5 TCM-6 TCM-4 EDL Target EFPA Design EFPA TCM-4 cancelled: If executed TCM-5 too small TCM-6 cancelled: Landing safety criteria all within desired limits Navigated final pre-entry EFPA determination: º ± 0.003°

IPPW-6 25 June 2007 Grover -8 Hypersonic Phase Rates during hypersonic and supersonic flight are within expected values Angle of attack reconstruction underway at LaRC Parachute Deployment Entry Interface

IPPW-6 25 June 2007 Grover -9 CFD solutions of Aero/RCS flow field shows potential for strong interaction –RCS Pitch authority is degraded and Yaw authority is low to non- existent (potential for control reversal exists) –Potential of large attitude at parachute deployment leading to excessive wrist mode dynamics impacting radar performance Mitigation recommendation was to open up control system deadbands during entry from early-Hypersonic regime through Supersonic regime to minimize/ eliminate RCS firings –Relying on inherent capsule stability to traverse flight regimes –There were no RCS firings from Hypersonic 2 through Lander separation Aero/RCS Interaction Issue

IPPW-6 25 June 2007 Grover -10 Parachute Phase Parachute deployment conditions: –Dyn. Press.:492 Pa –Mach:1.68 –Altitude:13.26 km As expected, “wrist mode” rates were high immediately after parachute deployment, but damped quickly Parachute Deployment

IPPW-6 25 June 2007 Grover -11 Phoenix on the Parachute - Spectacular! Image captured from orbit by Mars Reconnaissance Orbiter HiRISE camera Image shows EDL system 47 seconds after parachute deployment approx. 9.2 km above surface Phoenix is 20 km in front of Heimdall Crater Heimdall Crater (Diameter 10 km) Phoenix

IPPW-6 25 June 2007 Grover -12 Terminal Descent Phase Spacecraft Axes X-Axis Y-Axis Z-Axis Roll to landed azimuth Lander Separation Lander rates during terminal descent are very benign relative to worst-case simulation prior to landing

IPPW-6 25 June 2007 Grover -13 Tip-Up and Gravity Turn With BAM Extra delta-v in upwind direction BAM angle Small Magnitude Wind BAM Backshell Avoidance Maneuver EDL Modifications: Terminal Descent Subphase Evolution Horizontal velocity prior to Lander separation was ~15 m/s, so NO BAM Maneuver performed

IPPW-6 25 June 2007 Grover -14 MRO Surface Image South Backshell Parachute Lander Heatshield

IPPW-6 25 June 2007 Grover -15 Trajectory Reconstruction View Due North Vantage Point: 42 km Altitude View Due East Vantage Point: 15 km Alt. Trajectory Visualization Trajectory created by back propagation of 200Hz IMU data Influence of winds appears apparent during descent on parachute

IPPW-6 25 June 2007 Grover -16 Landing Footprint Last pre-entry footprint prediction: 56 x 20 km Design Footprint Requirement: 110 x 20 km

IPPW-6 25 June 2007 Grover -17 Baseline Simulation vs Flight

IPPW-6 25 June 2007 Grover -18 JPL & LaRC EDL Operations Team

IPPW-6 25 June 2007 Grover -19 Phoenix on the Northern Plains of Mars!

IPPW-6 25 June 2007 Grover -20 Back-Up Slides

IPPW-6 25 June 2007 Grover -21 PND-21 TCM thrusters used for Pitch/Yaw control RCS thrusters used for Roll control Phoenix Thruster Geometry

IPPW-6 25 June 2007 Grover -22 EDL Modifications: Terminal Descent Subphase Evolution New Requirement The distance between the center of mass of the lander and center of mass of the backshell shall be greater than 35m from 5s after lander separation to touchdown of both bodies 35m In cases of low wind and no wind terminal descent scenarios, there is an increased probability the backshell/parachute will recontact the lander –Issue existed for MPL and Mars ’01 EDL designs Parachute zone 30m Terminal Descent Redesign Driver